Art of treating rebellious ores of the precious metals.



UNITED STATES PATENT- OFFICE.

WILLIAM F. DOWNS, or JERSEY CITY, NEW JERSEY,

ART OF TREATING REBELLIOUS ORES OF THE PRECIOUS METALS.

SPECIFICATION forming part of Letters Patent No. 707,214, dated August 19, 1902.

Application filed November 27. 1901. Serial No. 83.835. (N0 specimens.) 7 I To all whom may concern:

city of Jersey Gityfin the county of Hudsonand State of New Jersey, have invented a new and useful Improvement in the Art of Treat,- ing Rebellious Ores of the Precious Metals, of which the following is a specification.

My invention relates to the extraction of the precious metals from ores containing rebellious elements. By precious metals I mean goldand silver. By rebellious elements I mean arsenic, tellurium, sulfur, and similar substances when they exist in such quantity and condition in the ore as to make it undesirable for'smelting purposes.-

The purpose of myinvention is more particularly to change such rebellious ores into non-rebellious ores by altering their condition with respectto the precious metals, whereby the latter are left distributed in a free state and the ore may be treated by the many economical and well-known processes then available.

I accomplish my purpose byintimately mixinga suitable quantity of the rebellious ore with a sodium compound and with an agent capable of releasing the sodium therefrom under the influence of heat and then heating the mixture to a temperature sufficient to release the sodium. A combination of the sodium and the rebellious elements takes place, the volatile impurities and compounds escape, and the precious metal is left distrib uted in a free state throughout the mass. It can then be recovered in the usual way.

. Forthe better understanding of my process I shall describe its application to the treatment of a gold ore containing arsenic, (the latter being a typical rebellious element,) the treatment being parallel to that which would take place in a similar ore containing sulfur, tellurium, or the like. In the method now commonly employed arsenic is eliminated from such an ore by'successive roastings.

This treatment is difficult and expensive and is attended by a considerable loss of gold. I do not dispense altogether with this treatment by roasting in my process, because a portion of the arsenic, sulfur, or tellurium may be readily removed at a comparatively low temperature and it isfdesirable to get rid of this portion as quickly as possible. It is the residuum of these materials remaining after the first roasting which is so difficult to eliminate and which it is the purpose. of my process to remove. e g

In practicing my invention the preliminary roasting of the ore is conducted as usual, (except in the case where the original ore is porous or friable enough to render such roasting unnecessary.) After this has been accomplished the partially-roasted ore is reduced to a finely-divided state by grinding or any similar well-known treatment. The grinding may, when deemed desirable, precede the roasting, as in the case of acoarse ore. I

similarly reduce to a finely-divided state asodium compound, preferably a'sodium salt, such as the carbonate. I also reduce to a finely-divided state the agent which I employ to release the sodium from its compound under the influence of heat,

The agent which I use is carbon, preferably in the form of charcoal. The'proportion of the sodium compound to the carbon in the mixture will of course be determined by the relation of their atomic weights according to the wellknown laws under which the subsequent reactions take place, and it must be chemically calculated or ascertained by previous experiment. I then intimately mix the finelyground ore with the sodium salt and charcoal, n

and under usual circumstances form th'emass into briquets of any suitable form and size,

having in mind the manner andplace in which the heat is to be applied in the subsequent steps of the operation.

account of its adhesive properties. In some cases it may not be necessary to form briquets. Assuming that the subsequent operations are to take place in a furnace, the briquets are then introduced into the furnace and subjected to the action of the heat. As the heat rises a point is reached where the 4 If it is found desirable, a small portion of milk of lime may be added'in the-formation of the briquets on' temperature is sufficient to release the metallic sodium, whereby a combination of. the sodium with the rebellious element in the ore results.

heat upon the mass has been such as to drive off such portions of the rebellious elements and their compounds as are removable at the In the meantime the action of the temperatures which have existed. The Volatile nascent sodium brought into intimate contact with the particles of the ore, which are usually porous, forms compounds with the rebellious elements which are either volatile and are driven 0% by the heat or soluble and may be removed by leaching while the gold is reduced to the metallic condition. Thus where arsenic is the rebellious element the sodium combines with it either as sodium arsenide, sodium arseuite, or sodium arsenate. The arsenide is volatile. The arsenite and arsenate are soluble. Hence the volatile compounds will be removed by heat and the non-volatile compounds by leaching. Of course if the presence of the non -volatile compounds does not interfere With the subsequent operations employed for the extraction of the precious metal they may be permitted to remain. By these steps the rebellious element has been changed to a non-rebellious condition, and the ore can then be subsequently treated for the recovery of the precious metal in any approved mannerfor instance, by cyaniding or chlorination.

It will be readily appreciated by those skilled in the art to which my invention relates that other alkali metals, such as potassium, will he the equivalent of sodium in carrying out my invention. a

What I claim as'new is 1. The process of treating ores containing precious metals and rebellious elements W hich consists in intimately mixing the ore with a sodium compound and an agent capable of releasing metallic sodium therefrom, heating the mixture to a temperature sufficient to release the sodium, whereby a combination of the sodium with the rebellious elements of the ore results and leaves the precious metal distributed in a free state throughout the mass, permitting the volatile impurities and compounds to escape and finally recovering the precious metal from the mass.

2. The process of treating ores containing precious metals and rebellious elements which consists in intimately mixing the ore with a sodium compound and an agent capable of releasing metallic sodium therefrom, heating the mixture to a temperature suflicient to release the sodium, whereby a combination of the sodium with the rebellious elements of the ore results and leaves the precious metal distributed in a free state throughout the mass, permitting the volatile impurities and compounds to escape, removing the non-volatile compounds formed and finally recovering the precious metal from the mass.

The process of treating ores containing precious metals and rebellious elements which consists in roasting the same, in intimately mixing the roasted ore with a sodium compound and an agent capable of releasing metallic sodium therefrom, heating the mixture to a temperature sufficient 'to release the sodium, whereby a combination of the sodium with the rebellious elements of the ore results and leaves the precious metal distributed in a free state throughout the mass, permitting the volatile impurities and compounds to escape and finally recovering the precious metal from the mass.

4. The process of treating ores containing precious metals and rebellious elements which consists in roasting the same, in intimately mixing the roasted ore with a sodium compound and an agent capable of releasing metallic sodium therefrom, heating the mixture to a temperature sufficient to release the sodium, whereby a combination of the sodium with the rebellious elements of the ore results and leaves the precious metal distributed in a free state throughout the mass, permitting the volatile impurities and compounds to escape, removing the non-volatile compounds formed and finally recovering the precious metal from the mass.

5. The process of treating ores containing precious metals and rebelliouselements which consists in intimately mixing the ore with a sodium compound and carbon, heating the mixture to a temperature sufficient to release the sodium, wherebya combination of the sodium with the rebellious elements of the ore results and leaves the precious metal distributed in a free state throughout the mass, permittingthevolatileimpurities and compounds to escape and finally recovering the precious metal from the mass.

6. The process of extracting gold from ores containing arsenic, tellurium, sulfur or similar impurities which consists in roasting the ores; reducing the roasted mass to a finelydivided state; making the powder so formed into briquets with suitable proportions of a sodium compound and carbon; heating the briquets to a temperature sufficient to release the sodium; removing the remaining compounds of sodium and the impurities, and recovering the gold from the residue.

W'itness my hand, this 21st day of November, 1901, in the presence of two subscribing witnesses.

WILLIAM F. DOWNS.

\Vitn esses:

HERMAN MEYER, MABEL K. WHITMAN. 

